Water-cooled lance or probe destined to be inserted into metallurgical furnaces

ABSTRACT

The invention relates to a water-cooled lance or probe destined to be inserted into metallurgical furnaces, comprising an inner tube, a concentrical outer tube and a guiding tube arranged between said inner and outer tubes for the formation of a coolant circulation, which lance or probe over part of its circumference and part of its longitudinal extension is exposed to increased heat influence. In the area of increased heat influence, the lance or probe is cooled to a greater degree by increasing the cooling area and the free current cross section there relative to the other parts of the lance or probe.

United States Patent [1 1 Smejkal May 13, 1975 WATER-COOLED LANCE 0RPROBE 3,080,755 3/1963 Percy 73/339 R x BE INSERTED INTO 3,250,1255/1966 Bonn i 73/359 X z i z fg g FURNACES 3,717,034 2/1973 Dukelow eta1. 73/343 R 3,742,763 7/l 73 Sczerba 73/343 R inventor:

Assignee:

Filed:

Hellmuth Smejkal. Linz, Austria Vereinigte Osterreichische EisenundStahlwerke Alpine Montan Aktiengesellschaft, Linz, Austria Aug. 6, 1973Appl. No.:

Foreign Application Priority Data Aug. 7, 1972 References Cited UNITEDSTATES PATENTS Austria 6789/72 Burton et a1. 136/231 PrimaryExaminer-Richard C. Oueisser Assistant E.ran1inerFrederick ShoonAttorney, Agent, or FirmBrumbaugh. Graves. Donohue & Raymond [57]ABSTRACT The invention relates to a water-cooled lance or probe destinedto be inserted into metallurgical furnaces. comprising an inner tube, aconcentrical outer tube and a guiding tube arranged between said innerand outer tubes for the formation of a coolant circulation, which lanceor probe over part of its circumference and part of its longitudinalextension is exposed to increased heat influence. ln the area ofincreased heat influence, the lance or probe is cooled to a greaterdegree by increasing the cooling area and the free current cross sectionthere relative to the other parts of the lance or probe.

8 Claims, 2 Drawing Figures PATENTED W I 31975 SHEEI 1 BF 2 FIG./

Pmimmum m 3.882.726

SHEEI 2 8F 2 PIC-i2 WATER-COOLED LANCE OR PROBE DESTINED TO BE INSERTEDINTO METALLURGICAL FURNACES The invention relates to a water-cooledlance or probe destined to be inserted into metallurgical furnaces,comprising an inner tube, a concentrical tube and a guiding tubearranged between said inner and outer tubes for the formation of acoolant circulation.

In refining processes, such lances are used for blowing a gaseousrefining agent, in particular pure oxygen, onto or into a hot liquidiron metal bath. With such lances also, missing heat can be supplied tothe refining process. Such means for the supply of solid, liquid and-/or gaseous fuel designed as burner lances have substantially the sameconstruction as oxygen blowing lances. The group of lances that may beused in metallurgical technology also includes probes for continuouslymeasuring the metal bath temperature, as described, for example, anAustrian Pat. No. 293,751 and No. 298,831. Measuring probes differ fromblowing or burner lanches with regard to their head. While lances areprovided with a jet or burner head, probes are provided with a probehead on which the measuring part containing a thermo-couple isreleasably fixed. The measuring part is immersed into the melt. Acompensating line is guided through the inner tube to connect thethermo-couple with an indicating means. Temperature measuring probes ofthis kind are further provided with a refractory protective brick(protective jacket) which is likewise releasably connected with theprobe head. The jacket extends over the greatest part of thelongitudinal extension of the measuring part and over the area where itis attached to the probe head. This protective brick protects themeasuring part against the attacks of the slag.

When water-cooled lances are put to operation in melting furnaces, inparticular in converters, great difficulties arise when part of thecircumference of the lance is subjected to a greater exposure to heatfor a short period or continuously. This is the case, for example, whenin an oxygen blowing converter, at a distance from a centrally arrangedblowing lance, a temperature measuring probe is arranged which immersesinto the hot liquid bath. The strong heat radiation issuing from theso-called burner spot exerted onto one side of the outer tube of thetemperature measuring probe, namely that turned towards the oxygenblowing lance, results in the distortion of the temperature measuringprobe. Owing to this heat exposure of one side, that side of theexternal tube which is turned towards the blowing lance is expanded to adifferent degree than that side which is turned away from the blowinglance, so that the material is stressed beyond its yield point and willbe disformed for ever. Thus, the temperature measuring probe isdistorted in a manner that the measuring point i.e. the lower end of theprobe slowly, from melt to melt, is moved in direction towards theblowing lance. This will lead to wrong measurements and, in case ofgreater distortions, lifting and lowering of the temperature measuringprobe or driving into or out of the converter may provide difficulties.So, it has not been possible to overcome the difficulties caused byone-side heat exposure of the cooling jacket of lances or temperaturemeasuring probes.

The invention is aimed at solving this problem and at creating awater-cooled lance or probe, in which the material of the lance or probewill not be stressed excessively on one side by the influence of heatand in which bending and distortion of the lance or probe is avoided,without changing the outer form of the lance or probe. The inventionshall be realized with simple means and without incurring greater costs.

In a lance or probe of the kind defined in the introduction, which overpart of its circumference and part of its longitudinal extension isexposed to an increased influence of heat, the lance or probe is cooled,according to the invention, to a greater degree in the area of increasedheat influence. In particular, the probe in this area is provided with agreater cooling area and a greater free current cross section than inits other parts.

For an increased cooling of the lance part which is exposed to increasedheat influence, the lance or probe is preferably provided with ribswhich are arranged in direction of thelongitudinal axis of the lance tobe heat conducting and-integral with the inner side of the outer tube.If desired the lance is also provided with a shellhalf which is arrangedat that part of the lance which is turned away from the increased heatinfluence, at the outside of the guiding tube so as to reduce thecurrent cross section for the cooling agent.

A preferred field of application of the invention is in a probe forcontinuously measuring the temperature of metal baths in converters,which may be inserted eccentrically from the top at a distance from ablowing lance into the hot liquid charge of the converter. A measuringpart and a refractory jacket surrounding said measuring part to protectit against the influence of slag are fixed to the probe head. In suchtemperature measuring probes, that part of the outer tube of the probewhich is turned towards the increased heat influence should have acooling area which is twice as big as that of the part of the outer tubeof the probe which is turned away from the increased heat influence.

A particular embodiment of such temperature measuring probes ischaracterized by the combination of the following features:

a. on the inner side of the outer tube half exposed to the increasedheat influence ribs are arranged having a length of at least 1500 mmwhich are preferably fixed by welding;

b. in the measuring position of the probe, the lower edge of the ribs isat a distance of maximally 500 mm above the hot liquid metal;

0. the thickness of the ribs substantially amounts to 0.4 .f,fbeing thewall thickness of the outer tube half;

d. the clear distance of the ribs in the middle area of the outer tubehalf, which corresponds to a central angle of 30 or to a width of d/2 ofthe outer diame- -ter of the tube half, amounts to maximally f 2 and istwice'as much in the two marginal areas.

Preferably the ratio of the free current cross section for the coolingmeans in the area of the circumferential zone exposed to, the increasedheat influence to the free current cross section in the area of theremaining circumferential zone is 1.75 1.

In order that the invention may be more fully understood, an embodimentthereof shall now be further explained by reference to the accompanyingdrawings.

FIG. 1 is a vertical sectional view of an oxygen blowing converter witha centrally arranged blowing lance and a temperature measuring probearranged at its side in measuring position.

FIG. 2 is a horizontal sectional view along the line ll-ll of thetemperature measuring probe on enlarged scale. It illustrates theconstruction of the probe in an area where one of its sides is exposedto increased heat influence.

Numeral 1 denotes a refractory-lined, preferably tiltable oxygen blowingconverter which contains a metal bath 2 covered with slat 3. Above themetal bath, a water-cooled blowing lance 4 is positioned centrally sothat by the oxygen blown onto the metal bath 2 a reaction zone 5 ofincreased temperature is formed which is called burning spot.Eccentrically in the converter, parallel to the oxygen blowing lance 4,a temperature measuring probe 6 is arranged to be liftable andlowerable. With its measuring part 7, which is releasably fixed to theprobe head, it is immersed into the melt 2. A refractory protectivebrick 8 surrounds the measuring part 7 and protects the measuring partas well as the joining place at the probe head against the influence ofthe slag 3 and the intrusion of hot liquid metal 2. That part of thewater-cooled jacket of the temperature measuring probe 6 which isgreatly stressed by heat radiation from the hot reaction zone 5 isdenoted with 9, while the opposite jacket part, which is less exposed tothe heat, is denoted with 10. In the area b of the probe, which areaextends in upward direction, at a distance a from the surface of the hotliquid metal 2, whereby a maximally amounts to 500 mm and b at least to1500 mm, according to the invention the interior of the temperaturemeasuring probe 6 is designed differently than the remaining probe part.

The probe is provided with an inner tube 11 which is connected with theouter tube, consisting of the tube halves 9 and 10, at the lower end bymeans of the probe head. Concentrically between the inner tube and theouter tube, a guiding tube 13 is arranged, which ends at a distance fromthe probe head so as to provide in a known manner for a cooling agentcirculation. in the annular space formed between the tubes 11 and 13,the cooling water flows downwardly to the probe head, where it isdeflected upwardly to flow back through the annular space formed by theouter tube 9, l and the guiding tube 13. The outer tube half 9 turnedtowards the hot reaction zone is connected to the opposite outer tubehalf by means of welding seams 12. In the area of the outer tube half10, which is less exposed to heat, a shell-half 14 is connected to theguiding tube 13 by means of welding seams 15. According to theinvention, the cooling effect is enhanced in the area of the outer tubehalf 9 which is more exposed to heat, which effect is achieved bywelding ribs 17 onto the inner side of the tube half 9 so that in theannular space the cooling area 16 is increased to about twice thecooling area of the opposite side. The length b of the ribs extending indirection of the longitudinal axis of the temperature measuring probe 6amounts to at least 1500 mm, as stated above. In the middle area of thetube half 9, corresponding to a central angle a of 30 or to a width ofd/2 (i.e. half of the outer diameter of the outer tube) the ribs 17 arearranged closely side by side. Their clear distance 0 depends on thewall thicknessfof the tube half9 and is to amount to maximallyf. Thethickness e of the ribs 17 also depends on f and should amount to about0.4.f. In the two marginal parts of the tube half 9, the clear distancebetween the ribs 17 is about twice as big as the area a, which meansthat it amounts to 20. The width of the ribs corresponds substantiallyto the clear distance between the guiding tube 13 and the tube half 9,i.e. there is only a small gap 21 in between. Owing to this arrangement,the cooling area 16 on that side of the probe which is turned towardsthe reaction zone 5 or to the blowing lance 4 is twice as big as thecooling area 18 on the opposite side 10, and the free current crosssection 19 for the passage of the cooling water on that side which isgreatly exposed to heat is about 1.75 times as big as the free passagecross section 20 on the opposite side. Thus, on that side of the probewhich is exposed to heat, a substantially greater amount of coolingwater is permitted to flow over the enlarged cooling area 16 so that anyexcessive heat stress is avoided there. Lances constructed according tothe invention thus will no longer be distorted or bent.

What I claim is:

l. A water-cooled lance for use in metallurgical technology, such as aprobe for continuously measuring the temperature of a metal bath,comprising an inner tube, a concentric outer tube, an intermediateguiding tube arranged between the inner and outer tubes so as to defineinner and outer annular passages through which a coolant can becirculated, and means for effecting differential cooling of twodifferent portions of a circumference of the lance along at least a partof the length of the lance, whereby a side of the lance exposed to agreater heat than an opposite side of the lance can be correspondinglycooled to a greater degree than said opposite side.

2. The lance set forth in claim 1, wherein the differential coolingmeans includes surfaces bounding at least one of the annular passages,said surfaces having a greater cooling area adapted to be exposed to acoolant adjacent a portion of the circumference of the lance adapted tobe exposed to a greater heat influence than adjacent other portionsofsaid circumference, and said at least one annular passage, said passagehaving a greater free current cross section for a coolant adjacent thatportion of the circumference of the lance adapted to be exposed to agreater heat influence than adjacent other portions of saidcircumference.

3. The lance as set forth in claim 2, wherein the ratio of the freecurrent cross section for a coolant in at least one of the annularpassages adjacent a portion of the circumference of the lance adapted tobe exposed to a greater heat influence to the free current cross sectionin said at least one of the annular passages adjacent other portions ofthe lance having a corresponding circumferential extent is 1.75 z 1.

4. The lance set forth in claim 1, wherein the differential coolingmeans includes a plurality of ribs extending in the direction of thelongitudinal axis of the lance and located adjacent a portion of thecircumference of the lance adapted to be exposed to a greater heatinfluence, the ribs being heat conducting and integral with an innerside of the outer tube.

5. The lance set forth in claim 1, wherein the differential coolingmeans includes a shell-half arranged around the exterior of the guidingtube so as to reduce the free cross section for a coolant in a portionof the outer annular passage adjacent a portion of the circumference ofthe lance generally opposite a portion of the circumference adapted tobe exposed to a greater heat influence.

6. The lance set forth in claim 1, wherein the lance is a probe forcontinuously measuring a temperature of a metal bath in a converter, theprobe being insertable into the metal bath vertically and alsoeccentrically relative to the vertical central axis of the converter ata distance from a blowing lance, the probe having a probe head and fixedto the probe head a temperature measuring element and a refractoryjacket surrounding said measuring element to protect it against slaginfluence, the differential cooling means including surfaces boundingthe radially outer periphery of the outer annular passage adjacent aportion of the outer circumference of the outer tube adapted to beexposed to a greater heat influence than other portions of said outercircumference, said surfaces having a cooling area adapted to be exposedto a coolant in the outer annular passage which is twice as large as acooling area that is also adapted to be exposed to a coolant in theouter annular passage, that is located opposite said portion of theouter tube adapted to be exposed to a greater heat influence, and thathas a circumferential extent equal to the circumferential extent of saidportion of the outer tube.

7. The lance set forth in claim 6, wherein the differential coolingmeans includes a plurality of ribs extending longitudinally of the lanceand attached to an inner surface of the outer tube adjacent the portionof the outer circumference of the outer tube adapted to be exposed to agreater heat influence, said portion of the outer circumference beingequal to one-half the outer circumference of the outer tube, the ribsbeing heat conducting and each having a length of at least 1500 mm., theribs also having a thickness of substantially 0.4.f, wherefis thethickness of the wall of the outer tube, and being circumferentiallyspaced apart a maximum distance off \[2 adjacent a central section ofsaid portion of the outer circumference of the outer tube, said centralsection having a circumferential extent defined by an arc subtended by acentral angle of 30, the ribs being circumferentially spaced apartadjacent marginal sections of said portion of the outer circumference ofthe outer tube on either side of said central section a distance equalto twice the corresponding circumferential spacing of the ribs in saidcentral section, the lance being adapted to assume a measuring positionin a converter such that the lower ends of the ribs are at a maximumdistance of 500 mm. above the surface of the liquid metal in the metalbath of the converter.

8. The lance set forth in claim 7, wherein said ribs are attached bywelding to the inner surface of the outer tube.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 2,726

DATED May 13 19 INVENTOR(5) I Hellmuth Smejkal It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below' Col. 1, line 7, after"concentrical" insert -0uter-;

Col. line 22 lanches" should read lances-;

Col.

Col. 1, line 62, after "So" insert -far;

3, line 8, "slat 3" should read -slag 3-; and

Col. line 54, "of the opposite" should read -on the opposite--,

fiigned and gealcd this fif Day of August 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN ff ('unmzissimu'r nflalenls andTrademarks UNTTED STATES PATENT OFFICE QERHHQATE 9F QURRECTIUN 6 PATENTNO. 2,726

DATED May 13, 1975 INVENTOR(S) Hellmuth Smejkal It is certrfied thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below' 6 Col. 1, line 7, after"concentrical" insert outer--;

Col, 1, line 22, 'lanches" should read -lances--;

Col. 1, line 62, after 50" insert -'-far-;

Q Col. 3, iL J' 1 e 8, "slat 3" should read slag 3-; and

Col, line 54, "of the opposite" should read --on the opposite--- fiignedand fiealed this fif h Day of August1975 Arrest:

RUTH C. MASON C. MARSHALL DANN A X lfi (nmmr'ssinnvr nj' lau'ms andTradcmurkx

1. A water-cooled lance for use in metallurgical technology, such as aprobe for continuously measuring the temperature of a metal bath,comprising an inner tube, a concentric outer tube, an intermediateguiding tube arranged between the inner and outer tubes so as to defineinner and outer annular passages through which a coolant can becirculated, and means for effecting differential cooling of twodifferent portions of a circumference of the lance along at least a partof the length of the lance, whereby a side of the lance exposed to agreater heat than an opposite side of the lance can be correspondinglycooled to a greater degree than said opposite side.
 2. The lance setforth in claim 1, wherein the differential cooling means includessurfaces bounding at least one of the annular passages, said surfaceshaving a greater cooling area adapted to be exposed to a coolantadjacent a portion of the circumference of the lance adapted to beexposed to a greater heat influence than adjacent other portions of saidcircumference, and said at least one annular passage, said passagehaving a greater free current cross section for a coolant adjacent thatportion of the circumference of the lance adapted to be exposed to agreater heat influence than adjacent other portions of saidcircumference.
 3. The lance as set forth in claim 2, wherein the ratioof the free current cross section for a coolant in at least one of theannular passages adjacent a portion of the circumference of the lanceadapted to be exposed to a greater heat influence to the free currentcross section in said at least one of the annular passages adjacentother portions of the lance having a corresponding circumferentialextent is 1.75 :
 1. 4. The lance set forth in claim 1, wherein thedifferential cooling means includes a plurality of ribs extending in thedirection of the longitudinal axis of the lance and located adjacent aportion of the circumference of the lance adapted to be exposed to agreater heat influence, the ribs being heat conducting and integral withan inner side of the outer tube.
 5. The lance set forth in claim 1,wherein the differential cooling means includes a shell-half arrangedaround the exterior of the guiding tube so as to reduce the free crosssection for a coolant in a portion of the outer annular passage adjacenta portion of the circumference of the lance generally opposite a portionof the circumference adapted to be exposed to a greater heat influence.6. The lance set forth in claim 1, wherein the lance is a probe forcontinuously measuring a temperature of a metal bath in a converter, theprobe being insertable into the metal bath vertically and alsoeccentrically relative to the vertical central axis of the converter ata distance from a blowing lance, the probe having a probe head and fixedto the probe head a temperature measuring element and a refractoryjacket surrounding said measuring element to protect it against slaginfluence, the differential cooling means including surfaces boundingthe radially outer periphery of the outer annular passage adjacent aportion of the outer circumference of the outer Tube adapted to beexposed to a greater heat influence than other portions of said outercircumference, said surfaces having a cooling area adapted to be exposedto a coolant in the outer annular passage which is twice as large as acooling area that is also adapted to be exposed to a coolant in theouter annular passage, that is located opposite said portion of theouter tube adapted to be exposed to a greater heat influence, and thathas a circumferential extent equal to the circumferential extent of saidportion of the outer tube.
 7. The lance set forth in claim 6, whereinthe differential cooling means includes a plurality of ribs extendinglongitudinally of the lance and attached to an inner surface of theouter tube adjacent the portion of the outer circumference of the outertube adapted to be exposed to a greater heat influence, said portion ofthe outer circumference being equal to one-half the outer circumferenceof the outer tube, the ribs being heat conducting and each having alength of at least 1500 mm., the ribs also having a thickness ofsubstantially 0.4.f, where f is the thickness of the wall of the outertube, and being circumferentially spaced apart a maximum distance of fSquare Root 2 adjacent a central section of said portion of the outercircumference of the outer tube, said central section having acircumferential extent defined by an arc subtended by a central angle of30*, the ribs being circumferentially spaced apart adjacent marginalsections of said portion of the outer circumference of the outer tube oneither side of said central section a distance equal to twice thecorresponding circumferential spacing of the ribs in said centralsection, the lance being adapted to assume a measuring position in aconverter such that the lower ends of the ribs are at a maximum distanceof 500 mm. above the surface of the liquid metal in the metal bath ofthe converter.
 8. The lance set forth in claim 7, wherein said ribs areattached by welding to the inner surface of the outer tube.